The German journal ”Cicero” has published an article on Habermas’ participation in the Nazi youth organisation ”Hitler Youth” in 1944, when he was 15. Jürgen Busche writes that Jürgen Habermas swallowed an incriminating piece of paper from his Hitler Youth days that a colleague of his from the time, Hans-Ulrich Wehler, handed back to him after the war. (Hans-Ulrich Wehler is a well-known professor of German history and a friend of Jürgen Habermas).

To "Süddeutsche Zeitung" (October 27, 2006) Hans-Ulrich Wehler says "Habermas was no Hitler Youth leader. For reasons of his harelip alone, he could never have had a leadership function under the Nazis. In actual fact, at 14 he did give first-aid classes in the Hitler Youth, for which he'd been trained as an orderly. His tasks included reminding participants who missed classes to attend punctually with so-called 'call letters.' These were preprinted forms in which the instructor simply had to fill in with the participant's information and then sign his name." [English translation by Sign&Sight.]

Wehler also denies that Habermas literally swallowed the form when he was confronted with it years later are false.

You can read Habermas’ own description of his participation in Hitler Jugend and his father’s ”sympathetic relation” to the Nazi regime in his book: ”Kleine Politische Schriften I-IV” (1981) pp. 511-12.